To start the discussion, the coolest technique I discovered so far is to let a LFO control the first step in a (gate or mono) sequence, while another LFO or sequencer frequently shifts the sequence to the right. Let this trigger slices in a sliced drum loop and you get crazy drum grooves in an instant.

Using all of the CV busses and CV In/Out modules to "stealthily" transport control signals between stacks.

Similary, using the Audio Out module (in InputOutput category) for Audio routing beyond each stack's 8 main aux outputs (which can of course be remapped per stack) and tapping aux audio off before each stack's primary output.

Putting a Pan & Volume before each audio Stack's output so I can trim the channel's gain before it reaches the stack's main volume control. This lets me keep as much of the main volume control's range usable for gain tweaks.